JPS6012057B2 - Method for sterilizing packaging materials and equipment for sterilizing packaging materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to L-sterile packaging, and more particularly to a method and apparatus for sterilizing packaging materials used to make containers for aseptic packaging of food products.

Examples of such packaging materials include cardboard, aluminum foil, and laminated paperboard consisting of layers of polyethylene.Aseptic packaging processes include heat treating metal cans and glass containers to sterilize them prior to filling. This is a generally accepted method.

However, most other packaging materials, such as plastics and plastic-paper combinations, are unstable at high temperatures and therefore require the use of alternative sterilization techniques and methods. A well known alternative method is the use of hydrogen peroxide and heat. In this regard, see, for example, U.S. Pat. 27
The germicidal action of ultraviolet radiation (UV) in the nanometer wavelength range is well known.

There are two types of such light sources that are commercially available and currently in widespread use. The first type is a conventional germicidal lamp to the second type is a high radiant intensity lamp. Several types of the former are commercially available. One of them is General. The high radiant intensity lamp commercially available from the Bovary Corporation (BBC) is a UV lamp that operates in the C region of the ultraviolet spectrum and is primarily a 254 nm lamp.
radiates energy in the area of The ultraviolet spectrum is conveniently divided into three regions, A, B, and C, with region C being the most biologically active region. = 1 rgs/sec).

Radiation dose is expressed as the product of radiation intensity and exposure time (minutes or sand), and is expressed as the product of radiation intensity and exposure time (minutes or sand), and is expressed as the product of radiation intensity and exposure time (minutes or sand).
sec/ground = 1 rgs/). Dose is commonly measured using photosensitive paper. Biological effects are measured using bioassays to determine which microorganisms survive after irradiation. The use of ultraviolet radiation as a sterilization method is not new.

For example ~U.S. Pat. Nos. 3,091,901 and 417
Please refer to No. 514. Such radiation
Ultraviolet light is also used commercially to sterilize food and liquid packaging materials. Ultraviolet light is also used to directly irradiate areas such as operating rooms and microbiology laboratories to control surface and airborne bacteria and bacterial contaminants. The above-mentioned BBC ultraviolet mC region lamp is currently used in Europe, for example, to sterilize various containers and cups in aseptic food packaging. The use of ultrasound is becoming widespread in the field of dentistry and dentistry as a means of improving the killing ability of disinfectants.

Diagnostic technology has a wide range of applications, including use in sterilizing surgical instruments and descaling teeth. An example of using ultrasound for cleaning glass containers is US Pat. No. 3,302,655.
It is stated in No. 5. The use of ultrasound to clean human hands is also described, for example, in U.S. Pat. The use of ultrasonic waves (using hydrogen peroxide) is known, for example, in US Pat. No. 3,929,409. ``The practical limitations of each are its unique killing ability and the length of time required to produce a given effect.''

However, ``What we now know is that if ultraviolet irradiation is applied immediately after ultrasonic treatment of paperboard laminates, the time required for sterilization is extremely shortened and an efficient sterilization technique is obtained. Another advantage of sterilization is that it can be used to sterilize materials that are not compatible with chemical sterilizers, which may have undesirable properties. It can be used to sterilize.Next, let me explain about Figure 1.

The microorganism used was Bacillus subtilis
A bacterial culture medium containing 1.5% soil extract (N
The cells were cultured on slants of UtrientAgar (Diflo). On slopes, 4 to 35°C until maximum sporulation.
It was cultured for 5 days. Sporulation is caused by Bartholomew and Mjttiwer.
This was determined using the cold spore staining method. For the ultrasonication portion of the experiment, a thermal ultrasonicator, model W-375, was used.

This device operates at a sonication frequency of 20 KHz with a maximum power of 375 Watts. The tip used was a 1.27 inch (1 inch) Disruptor'horn (
disruptor hom).

A high intensity ultraviolet lamp was used, commercially available from Braun Bovary Corporation (BBC) of Switzerland.

The model used was Braun Bobari irradiation device ultraviolet-CI.
It is 3-50. It is a lamp type x122-50 mounted in a watertight housing containing a reflector and a water cooling device. Quartz glass windows absorb ~1 ultraviolet radiation.
It transmits only in this direction and has an efficiency of 99.9% at 254 nm. For experiments using hydrogen peroxide and heat, use a stabilized solution of 30% hydrogen peroxide (target
Electronic grade) was used.

Seed 20 μm of the spore suspension on one side of the test plate,
One inoculum 11 was applied and allowed to dry for 30 minutes. After drying, 1M of the plates were subjected to ultrasonic treatment using an ultrasonic processor 12. Unless otherwise stated, ultrasonic treatment is performed only when the output level is 6.
．． It was 5-7 watts and had a duration of 19 seconds. Sonication was performed in a sterile petri dish 14 using sterile distilled water 16 as the sonication medium. After ultrasonication, excess moisture was removed and the test plate IQ was prepared using the BBC type 13 described above.
150 ultraviolet lamps were placed on a table at a distance of 15.24 (6 inches) from the light surface, and ultraviolet light was irradiated for a predetermined period of time (usually 19 hours). In order to check the number, "Plate 101 was subjected to a second ultrasonic treatment.

To count viable microbial cells, the sonicated solution was spread over a suitable culture plate 20'. The plates were incubated at 390 for 4 hours. Cell counts were performed after 2 hours and 4 hours. A spore suspension of 20 tubes was inoculated into one test plate to give a spore concentration of 20 days and 20 days in the case of hot air treatment.

The test plate 10 was immersed in 30% 02 to 1 part, and excess hydrogen peroxide solution was removed.

The test plate 10 was then held under a hot air blower for 8 seconds. Temperatures varied from 150 pm to 155 qo. After exposure to hot air, the test plates were rinsed with sterile distilled water and then placed in sterile distilled water and subjected to 19-sand spacing sonication at a power of 7 watts to remove any remaining cells. The rinsing solution and sonication solution are mixed into a plate count culture medium (
It was spread using Plap Count Agar (Difco). The plates were incubated at 35°C for a total of 4 hours. Cell counts were performed after 2 and 4 hours. Microbial Treatment The material used for all tests was laminate paperboard with metal foil and polyethylene coating, which is commonly used for packaging juices and juice drinks.

The layer structure is as follows. That is, (low density) polyethylene (outer layer)/paperboard/Surlyn/(low density) polyethylene (inner layer). (Surlyn (Sml)) ``DuPont (DuPont) on thermoplastic resins with ionic crosslinking derived from ethylene-methacrylic acid copolymers.
Pont). The test board is ``4.5 skin 5.0
It was cut in a flowing manner.

The inoculation site is an area of 1.5 squares in the center of the test plate. One cell suspension of 20 mucs was used to give one inoculum per inoculation site. The suspension was distributed as evenly as possible over the inoculation site with a rubber policeman and allowed to dry for about 30 minutes before testing. After each test, cell counts were performed to determine the number of viable microorganisms. Counts were performed both in the sonication solution and in the sterile water used to rinse the treated test plates. In order to investigate the order of ultrasound irradiation and its contribution, we studied the effects of applying them in succession.

According to the results in Table 1, when the packaging material was inoculated with one armlet and only ultrasonic vibration was applied, the logarithmic reduction rate of microorganisms was 0.5, compared to that when UV radiation was applied. It can be seen that the logarithmic reduction rate of is 2.9. Table 1: Effect of sequence of ultraviolet irradiation and ultrasonic treatment on bactericidal properties When the test plate was exposed to ultrasonic vibration for 19 sand intervals, followed by ultraviolet irradiation for 1 current sand interval, the logarithmic reduction rate of active microorganisms was 5.4 ~ a fairly large decrease was observed.

When treated in the reverse order, the results were the same as with ultraviolet radiation treatment alone. In order to investigate the reproducibility of the sterilization method, the inoculated test plates were subjected to ultrasonic vibration for 19 days, followed by ultraviolet irradiation for 19 days, using 5 different treatments.
I followed the seal and went. Ultraviolet irradiation alone was used as a control in the experiment. The results in Table 2 show that the number of spores inoculated on any day consistently decreased to the level of 1 microorganism, and the logarithmic reduction rate was 5.1, which is approximately twice the effect of UV irradiation alone. It shows that there is. (Thus, it was found that the logarithmic reduction rate was 2.5 greater than that of spores that received only UV irradiation.) Table 2: Effects of UV irradiation and ultrasound treatment on the survival of Bacillus, Subtilis, Vivi, and Niga spores. Effect: 5-day study Next, we compared the bactericidal effects of hydrogen peroxide (day 202), hydrogen peroxide heating, ultraviolet rays, and sonication with ultraviolet rays.

With hydrogen peroxide being a common disinfectant used for sterilization, Bacillus subtilis buibi niger spores were allowed to act on the hydrogen peroxide and then heated for 9 seconds at less than 100 qo (to prevent the polyethylene layer from melting). As a result, the logarithmic reduction rate of active cells is 5. The breasts were firm (Table 3). Table 3:
Comparison of the bactericidal effects of hydrogen oxide (2020), ultraviolet irradiation, and occasional ultraviolet irradiation + ultrasonic treatment Hydrogen peroxide alone or heating alone had no significant effect on the test microorganisms. .

Again, we show that the combination of ultrasonication and UV radiation reduces active cells to a greater extent than UV radiation alone. It was found that the exposure time had no effect on the killing efficiency of this method when added to the bacterial spores (Table 4).

Table 4; Bacillus, Subtilis, Buibui, etc. when applied with ultrasonic vibration at various intensities and duration
Niga→1) Logarithmic reduction rate of spores Exposure time (1) Original inoculum 3.6×1 (2 Ultraviolet irradiation time = 10 seconds Intensity did not affect sterilization efficiency.

There was a significant increase in log reduction between 0.7 and 110 watts, but no appreciable difference occurred using higher intensities.

The effect of the length of UV irradiation time was found to be quite variable.

Table 5: Logarithmic reduction rate of spores of Patillus, Subtilis, B. niger (1) when ultraviolet irradiation is applied with various irradiation times along with ultrasonic treatment (2) (1) Initial inoculum (average) = 3 .4 x 108 (2) The time of applying ultrasonic vibration is 6.5-7.0 watts and 1
It was 5 seconds.

The bactericidal effects of ultraviolet rays and ultrasonication gradually increased as the action time increased up to i-stone sand.

In each of the tests summarized in Tables 1-5, the BBC UV radiation units 13-50 described above were used.

The apparatus for carrying out the sterilization of packaging materials according to the present invention includes a liquid dish, a device for continuously moving the packaging material in and out of the blood, and a liquid pad for transmitting ultrasonic energy to the liquid. contacting at least one surface of the portion of the packaging material with the liquid such that at least one surface of the portion of the packaging material is exposed to ultrasonic energy; an apparatus for drying said packaging material after said packaging material has moved out of said vat; and at least said drying packaging material to produce a sterile packaging material used for aseptic packaging. an apparatus for exposing the ultrasonicated surface of the ultraviolet radiation apparatus to an ultraviolet radiation apparatus.

Figure 2 illustrates how the present invention can be applied to a continuous process for sterilizing strips of material for packaging foods, etc. Everything is aseptically shaped, filled and sealed into individual containers.

In FIG. 2, the reference numeral 32 also indicates a roll of laminate material of the type described above, for example.

After the supply roll 3 is pulled out from the bonito, the belt-like weight moves and passes around the row, and the liquid 3 rudder is introduced.
Ultrasonic energy is then emitted through the solution by an ultrasonic processor 38 or by an ultrasonic treatment bath device (not shown) contained within the dishwasher. Although it is possible to apply ultrasonic energy to the entire band-shaped pot, it is preferable to expose at least the surface of the band-shaped body forming the inner surface that contacts the food to ultrasonic energy. It will be clear that drying means other than an air knife, such as an air knife or an air knife, can be used for this step of the operation.
It will also be clear that the ultrasonic processor conductivity corresponds to the ultrasonic processor conductivity in the electrical diagram. Ultrasonic treatment The strip that has been subjected to ultrasonic treatment and has come out of the liquid base passes through the vicinity of the ultraviolet light source indicated by reference number 2 even after being dried by an air knife. The element Turtle Breast in Figure 2 corresponds to the element Furai Nona in the electrogram. Thereafter, the strip is placed into a molding and filling device. Form-fill equipment is generally used to form tubes from strips, fill them with sterile food, cut and seal them to produce individual sterile packaged products. The device is described in U.S. Patent No. 3709
56y beast is described. Generally speaking, the present invention is directed to a method of sterilizing packaging material, which, following its sterilization treatment, is used for the aseptic packaging of food products.

The method consists of the steps: ■ first subjecting the packaging material to ultrasonic vibrations through a liquid medium; and ■ then exposing the packaging material to ultraviolet radiation, the steps being combined as sequential steps in the order described. The bactericidal effects of methods ① and ① are characterized by being greater than when they are carried out in the reverse order. A simple explanation of the drawings: Figure 2 shows the basic steps of the sterilization process of this invention. FIG. 3 is a diagram showing how the process of the present invention is applied to continuous processing.

The reference numbers for the main elements in the figure are as follows.

The Q-M test plate is also military 2...Ultrasonic treatment machine ``Tofu 4...Thermic bacterium petri dish is also sterile distilled water on the calcar fin side'' The back fake W ultraviolet lamp is also 3
81.9 Supply rolls 82...packaging material strips 4...bath liquids...blood...ultrasonic processors and kameha...air knives...ultraviolet light source, 44...forming and filling equipment Mo4gekon sterile packaging products.RG・Noboru FIG, 2

Claims (1)

[Claims] 1. A method for sterilizing a packaging material in aseptic food packaging, comprising: (1) first passing the packaging material through a liquid medium and applying ultrasonic vibration; applying ultraviolet radiation to the material, subsequently forming the packaging material into a tube, then filling the tube with a food product, and sealing the tube to produce individual sterile packages filled with the food product; A sterilization method characterized by: 2. The sterilization method according to claim 1, wherein the step (1) is carried out at an ultrasonication frequency of 20 KHz. 3. The method of claim 1, wherein step (1) is carried out at a power level in the range of 0.7-145 watts. 4. Claims 1 and 2, characterized in that said step is carried out for a duration in the range of 1-60 seconds.
The sterilization method according to any one of paragraphs 1 and 3. 5. Sterilization method according to claim 2, characterized in that step (2) is carried out with ultraviolet radiation in the wavelength range of 250-270 nanometers for a duration of 2-15 seconds. 6. The sterilization method according to claim 1, wherein the packaging material is a laminated material having at least one layer of paperboard. 7. The laminate comprises a first thermoplastic material layer, a paperboard layer, a second thermoplastic material layer, a metal foil layer, a third thermoplastic material layer, and a fourth thermoplastic material layer. The sterilization method according to claim 6, characterized in that: 8. The sterilization method of claim 7, wherein the first and fourth thermoplastic material layers are made of polyethylene. 9. The sterilization method according to claim 8, wherein the second and third thermoplastic material layers are made of a thermoplastic resin having an ionically cross-linked structure. 10. The sterilization method according to claim 1, wherein the liquid medium in step (1) is water. 11. In the case where the packaging material is a strip of infinite length, and the strip is used for manufacturing the package, which is filled and sealed one after another after sterilization, (1) first, (2) sonicating at least one side of said strip by applying ultrasonic vibrations through a liquid medium; and (2) then sonicating the sonicated side of said strip by applying ultraviolet radiation. At least the surface of the strip-shaped body is subjected to ultrasonic treatment, and then the surface of the strip-shaped body is irradiated with ultraviolet rays, and the one side of the strip-shaped body is
A sterile packaged food forming the inner food contact surface of the sealed package is produced, and the bactericidal effect of steps (1) and (2) combined as a continuous process in the above order is better than if the order was reversed. 2. The sterilization method according to claim 1, which is carried out continuously, characterized in that the sterilization method is performed continuously. 12 the packaging material is a laminate, the laminate forming an inner layer of the sealed package, a first thermoplastic material layer, a paperboard layer, a second thermoplastic material layer, a metal foil layer; Third
12. The method of claim 11, further comprising a fourth layer of thermoplastic material forming the outer layer of the sealed package. 13. An apparatus for sterilizing packaging materials in aseptic food packaging, comprising: a liquid dish; a device for continuously moving the packaging material in and out of the liquid dish; and a device that applies ultrasonic energy to the liquid. an ultrasonic treatment device within said liquid dish for transmitting at least one surface of said portion of said packaging material and said liquid so that at least one surface of said packaging material is subjected to the action of ultrasonic energy; an apparatus for maintaining contact with the packaging material; an apparatus for drying the packaging material after it has been moved out of the dish; and a device for producing a sterile packaging material used for aseptic packaging. A sterilization device comprising: a device for subjecting at least the ultrasonicated surface of the dry packaging material to the action of an ultraviolet radiation device. 14. Claim 13, comprising an apparatus for forming a container from the packaging material, the inner surface of the container having a surface subjected to ultrasonic treatment and ultraviolet radiation. Sterilization equipment as described in section. 15. A sterilization device according to claim 14, characterized in that it includes a device for filling containers of sterilized food. 16. The sterilization device of claim 13, wherein the ultraviolet radiation device generates ultraviolet radiation in the wavelength range of 250-270 nanometers. 17. Claim 13, wherein the liquid dish is a dish containing a liquid that does not contain a chemical disinfectant.
Sterilization equipment as described in section. 18. The sterilizer according to claim 13, wherein the liquid dish is a dish containing water. 19. The sterilization device of claim 13, wherein the ultrasonic treatment device generates ultrasonic vibrations in a power range of 0.7 to 145 watts. 20. The sterilization device according to claim 13, wherein the frequency of the ultrasonic treatment device is approximately 20 KHz. 21. The sterilization device according to claim 13, wherein both surfaces of the packaging material are immersed in the liquid in the dish.